I have 3 PLC's and an NS10 HMI on an Ethernet network.
They communicate with each other just fine and I can communicate with the PLC's from my laptop.
I cannot transfer to or from the PT over Ethernet. USB and serial work fine.
My wired local network adapter is number 1 in the list of adapters.

The I.P.s of the devices are sequential, i.e. PLC1 XXX.XXX.90.35, PLC2 XXX.XXX.90.36, PLC3 XXX.XXX.190.37, HMI XXX.XXX.90.38. Subnet masks are all 255.255.0.0.

Evanmars

Is PLC 3 190.37 or 90.37?

This could be one of several things:
1. CX Designer does not always select the correct Ethernet adapter to use for downloading on Ethernet. Try turning off your wireless card, if this is enabled.
2. It could be the class B subnet. Because you are not spanning multiple segments, you should be able to set 255.255.255.0 as the subnet. If you need to keep the class B subnet, add an entry in the FINS / IP conversion table of the NS that lists your PC's IP address. This will require a static IP address for the PC.

Can you be more specific about what happens when you try to transfer on Ethernet? If you try 2 times in a row, do you get a message on CX Designer indicating that you are already connected? What is the IP address of the PC?